Mood disorders are among the most pervasive and intransigent of all psychiatric conditions, conferring an extraordinary burden of disease and a widespread negative impact on quality of life and productivity. While professional interventions have improved many sufferers' lives, a high number of individuals seek out additional support in peer-led, community mental health mutual-help organizations (MHOs), such as the Depression and Bipolar Support Alliance (DBSA). Extrapolating from MHO research in the addiction field24, mental health focused MHO participation could potentially represent a cost-effective clinical adjunct to professional care, but has not been systematically evaluated. DBSA is the largest existing mental health MHO in the U.S., providing ongoing peer-led recovery support during thousands of group meetings each week. MHOs may aid long-term psychiatric stabilization by providing informal monitoring, personal accountability, a sense of community, rich social support, exchange of recovery information (in-person and online), and continuous cost free services24. However, despite the common goals of DBSA and professional efforts to support remission and recovery, nothing is known from a scientific standpoint about their combined clinical impact and how MHO participation may extend or potentiate the effects of professional treatments. Lessons learned from the substance use disorder (SUD) field suggest there is potential that greater professional linkage to mental health MHOs, like DBSA, could enhance patients' mental health outcomes and reduce healthcare costs - a highly favorable combination that is in keeping with the goals of the Affordable Care Act (2010) and emerging Accountable Care Organizations (ACOs). In the absence of evidence, however, these potentially valuable and widespread community mental health resources may be under-utilized, to the detriment of patients, families, the health care economy, and society at large. The long-term goal of this line of research is to develop and test a clinical intervention designed to engage patients with DBSA to determine whether clinical linkage improves functioning and quality of life, and reduces health care costs among those suffering from mood disorders, as participation in Alcoholics Anonymous (AA) has been shown to do among those suffering from SUD24. However, given the absence of any systematic empirical evidence on who uses DBSA or on DBSA's ability to engage and retain individuals and confer benefit, this R21 is a necessary first step. To this end, this study proposes the following specific aims: 1. To conduct a cross-sectional survey of DBSA participants (N=200); 2. To provide estimates of rates of attendance, retention in, and discontinuation from, DBSA, for new DBSA attendees (N=60) with mood disorders over a 6-month follow-up and examine which patient sub-groups (e.g., depressed/bipolar, men/women, psychiatric severity etc.) appear most likely to engage/discontinue. 3. To conduct a prospective between-group study of new DBSA members (N=60) and matched controls (n=100; matched on age, gender, mood disorder, psychiatric severity) in order to examine the degree of benefit attributable to DBSA participation over a 6-month period).